3G mobile contracts can be for wireless data cards to get your computer on the Internet, or for the data plan on your mobile phone. In order to get data to either of these devices most mobile providers require you to sign a two or three-year contract for data to the device. If your contact isn't up yet but you would still like to get out of your contract, there are a few things you can do to make that happen.
Return your 3G data card or phone to the store within 30-days of purchasing it. If you are not satisfied with your 3G phone or data card within the first 30 days you are legally allowed to return the phone and cancel your contract in the process. Some carriers may charge an open box fee for returning the phone.
Port your number to another carrier. If you port your 3G data plan, or just the phone number associated with your 3G plan over to another carrier, then your original contract will be cancelled. Most mobile phone carriers charge an early termination fee of £9-$200 for contracts that are ended before their term, so expect a bill to come in the mail soon.
Call your 3G provider and express your desire to cancel your 3G plan. If you have a 3G data plan on top of a voice plan, your provider may allow you to drop the data plan and keep the voice portion of the plan without paying an early termination fee.
Visit a store for your carrier and talk to a customer service representative about cancelling your 3G contract. The carrier representative can let you know exactly how much time you have left in your 3G contract and can advise you on what might be the best plan of action for you to do to go about cancelling it. If you are cancelling your contract for monetary reasons a customer service representative may be able to offer you discounts or other promotional prices to keep you as a customer.